1. Department of Neurosurgery, Huashan Hospital, Fudan University, Shanghai, People's Republic of China;
2. Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland;
3. Department of Orthopedics, Xinqiao Hospital, The Third Military Medical University, Chong Qing, People's Republic of China; and
4. Department of Neurological Surgery, The Ohio State University, Columbus, Ohio